


Cuckolding Isn't Just for Men Anymore

by TheMadKatter13



Series: Kinktober 2017 [5]
Category: Sherlock (TV)
Genre: Alternate Universe - Canon Divergence, Anal, Anal Fingering, Anal Sex, Canon Universe, Cuckolding, First Kiss, First Time, Kinktober, Kinktober 2017, Kissing, M/M, POV Mary Morstan, POV Outsider, Plot What Plot/Porn Without Plot, TECHNICAL John/Mary, but only in that they're married, jealous mary
Language: English
Status: Completed
Published: 2017-10-06
Updated: 2017-10-06
Packaged: 2019-01-09 17:23:59
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,001
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12281061
Author URL: https://archiveofourown.org/users/TheMadKatter13/pseuds/TheMadKatter13
Summary: “You’re going to invite Sherlock over for tea, and then you two are going to have sex while I watch.” As could be expected, John promptly choked on his morning coffee.





	Cuckolding Isn't Just for Men Anymore

**Author's Note:**

> I'm pretty sure this idea has been somewhere in my Docs for at least a year, if not more, and lucky me, I remembered I had it and could use it for today's prompt.

> Day 06: Humiliation | **Cuckolding** | Body Swap

There were best friends, there were lovers, and then there was her husband and Sherlock Holmes. It was a good thing Mary wasn't a jealous woman because she wasn't 100% confident that John would choose her over his best friend. Which is why she said what she did one morning as she buttered her toast.

“You’re going to invite Sherlock over for tea, and then you two are going to have sex while I watch.”

As could be expected, John promptly choked on his morning coffee.

* * *

"Good evening, Mary," Sherlock greeted as he stepped through their front door.

"Sherlock," Mary greeted back warmly, pulling the too-tall man into a hug as she pressed a kiss to his cheek. It was also a good thing that she liked Sherlock, otherwise this would have been painful and frustrating on multiple levels. "John's in the bedroom. I'll be in a moment; just need to pop into the kitchen for a glass of wine."

He stared at her as he stripped off his gloves and coat, and then nodded as he hung it on the hook and strode deeper into the flat.

Mary hummed to herself as she poured herself a glass and took her time walking back into the bedroom, hoping they'd already gotten started without her. But when she walked in the door, she found John sitting on the edge of the bed, staring at his twisting fingers, and Sherlock standing at the far corner, looking distinctly uncomfortable in that way he had when he didn't want anyone to know he was uncomfortable.

"Don't hesitate on my account," she said mildly as she sat in the armchair in the corner. They both looked up at her and she held their general gaze as she took a sip. When they didn't move, she spoke again, letting a faux impatience colour her voice. "I'm waiting," she said with a wave of her wineglass.

Sherlock finally moved, walking slowly over to stand between John's legs, and John looked studiously anywhere but at Sherlock, whose groin was almost directly in John's bright red face. Then they both stopped and Mary sighed. She just wanted to enjoy the show, not direct it.

"Why don't you start with kissing?" she suggested, hoping it would jumpstart them. 

It was another long moment of twitchy eyes and fingers and shifting feet, before Sherlock finally bent down to press a boringly-chaste kiss to John's lips. John startled backwards and stared at Sherlock for a long moment before he suddenly lurched forward and pulled Sherlock back down to him. Fantastic. She was right.

They were fascinating to watch, really. When her and John made love, he was nothing but careful and attentive, but with Sherlock, he was… hungry. Desperate. Neither of them could pull their mouths apart for very long before they returned, even as their hands wandered, tugging at clothes, pulling and even ripping in some cases. Rather quickly, especially for how long it took them to start, they were both naked, John's familiar landscape ignored for the unfamiliar sight of Sherlock's skin.

Sherlock was even paler underneath his clothes than his hands and face indicated, and it was covered with a great deal more scarring than she'd really expected. Then again, Sherlock still hadn't truly divulged what he'd done during his absence. Or if he had, he hadn't told John, or John hadn't told her. It looked like he'd been tortured, marks like whips stretching across the skin covering shifting shoulders as he went down on John, swallowing his cock as he pressed a shining finger into John.

John was staring resolutely at the ceiling, hands fisted at his sides and his jaw tight, like he was just soldiering through it. But he was as Sherlock was, and had been ever before Sherlock had set his mouth to him. His face was red, and Mary wondered if it was from pleasure or embarrassment. They were both eerily silent, and Mary so desperately wished they would make a sound, any kind of sound, but the only noise coming from the bed was from Sherlock apparently deep-throating John's frankly-thick cock, and from the two fingers now pumping in and out of her husband. Mary just wanted to see what they would be like if they got the chance to actually be together.

It was almost funny, how adamantly John had denied her the opportunity to peg him, no matter how much she'd asked, and yet, he hadn't put up anywhere near half the fight when Mary had first declared that this was going to happen. Or for that matter, any point after. For all his talk, John wanted this. Just as much as Sherlock did. Mary didn't have it in herself to wish that they'd pulled their heads out of their arses before now because if they had, Mary would never had gotten John. At least now, they could both have him. So to speak.

" _John_ ," Sherlock moaned suddenly, and Mary realized her thoughts had wandered and she'd missed the initial penetration. Sherlock was fully seated inside John, expression blissed out whereas John's was still flaming red and a bit pinched.

They made quite the sight, Sherlock with all his pale skin kneeling between John's darker thighs, knees pushed up to his chest and hands hooked in the crooks to keep them up. It was rather arousing, actually, seeing them together like this. Mary licked her lips and took another drink.

"Move, Sherlock," John gritted out through his clenched jaw. It almost made Mary want to tsk in disapproval and disappointment, but her part in this scene was to sit back and watch Sherlock give John the pleasure she could not. To her slight surprise, Sherlock took up the reproval instead, sliding a hand up John's chest to palm his throat as he bent down and forced John, however unwillingly, to accept his kiss. He didn't let up until John was squirming on his cock and panting into his mouth, chest heaving below his and fingers creating pale dimples on his back.

Shelrock's first thrust made John moan in a way Mary had never heard and it sent an unexpected wash of black jealously through her, her face pulling into a frown against her will and her fingers tightening around the stem of her glass. Logically, she knew that the pleasure from prostate stimulation was different than that gained from penile-only stimulation, but it suddenly irked her that John would only allow Sherlock to give that to him and not here. And giving it to him was exactly what Sherlock was doing, with firm, hard thrusts that kept knocking the headboard into the wall in a steady rhythm. John was even starting to moan and whimper, eyes squeezed shut as he tried to rock into Sherlock's every movement, but it was clear even from where Mary was sitting that all he could do was hold on for the ride.

When Sherlock bent his head to begin sucking dark marks into the skin of John's neck and shoulders and chest, Mary had to force herself to remain silent and take a large gulp of her wine, which was disappearing a quicker rate than she'd anticipated. But she also hadn't anticipated correctly how this would make her feel either. She was okay with it, she really was, but it stung that she never got John to sound like that, that Sherlock could so easily, that John was clinging to him as if Sherlock was the only thing keeping tethered. She really should have insisted on some rules, but when she pictured this, she'd only pictured something similar to what her and John engaged in; that is, soft, loving sex and absolutely no markings. Sherlock wasn't even wearing a condom, at John's surprising insistence after he'd verified that the former addict was clean. Which meant that Sherlock was going to come in John, marking him in a way, and in a place, that Mary never could.

Suddenly, she became aware that Sherlock was whispering, but even in the otherwise silent room, she couldn't hear him over the squelch of his cock fucking into her husband and the knock of the wall. And try as she might to make out the quiet words, once she took notice of that squelch, it was all she could hear, and a glance at the source turned into a stare. From where she sat, she could see every stroke between Sherlock's legs, and the sight made it click that someone else was touching her husband that wasn't her. It had been her idea, but that dark jealously in her chest was making her regret ever opening her mouth. She wished she could have properly anticipated this.

"Sherlock, fuck, please please please," John begged, his voice louder than Sherlock's had been, rasping and desperate.

"I want you to come on my cock, John," Sherlock replied, these words audible. It made that jealousy flare, wondering what he'd been saying before, why he hadn't wanted to her to hear him. "If wanted a touch on your cock to make you come, you should have gone to Mary. But _I'm_ fucking you and you'll come on _my_ cock or you won't come at all," Sherlock decreed, voice more possessive than it had any right to be. But Mary couldn't say anything.

"Jesus christ, Sherlock, I- I- I can't," John stuttered, flinging his head back.

"You can," Sherlock insisted. He knelt upright and dragged John just a little onto his thighs and John cried out in surprise, back arching off the bed as come shot from his cock, splashing his belly and his chest and all the way up to his chin. "Yes, John," Sherlock muttered, pace increasing as John writhed and kept coming. "Yes yes yes yes _yesss_ ," he hissed, and then slammed to a stop, only to push in again, and again and again, each time a little slower than the last before he fell still. Finally, John collapsed to the bed, panting hard.

"Christ," John breathed, sounding winded like he only did after very, very good sex. She could count on one hand the number of times she'd heard him sound like that.

Sherlock hummed as he settled down on top of him, still inside him, each shift pushing drops of semen out of John's hole. He lifted a hand and stroked his fingers through John's hair as he drew him into a one and then another and then another until they seemed to melt together and Mary was greeting her teeth.

It felt like hours before Sherlock pulled away in fits and starts of shorter and shorter kisses. He pulled out and slotted himself against John's far side, curling around him as John turned towards Mary with a soft, slightly nervous smile.

"I wasn't sure about this at first, but you were right Mary, as usual," John said, voice tired but pleased. And suddenly Mary knew she had made an error. Because even though it would take a while, before John carefully broached the topic of it happening again, asking for it without asking for it, it would happen again. Of that, she had no doubt. Only time would tell if it was a fatal error, so to speak, because with as much love as she gave to John, she wasn't sure if it was enough. It used to be that, between her and Sherlock, only she could give John sex. But now, what they could contribute to John was equal.

"Of course I was right," she said, voice as confident as she wasn't before she downed the rest of her wine.

Both John and Sherlock smiled at her and then Sherlock cupped John's cheek and turned his head around to kiss him again. As Sherlock bent his head down, his eyes flicked to Mary's… and then he smirked.

Mary's wineglass stem snapped in her hand. It seemed she was a jealous woman after all.

FIN

**Author's Note:**

> Not bad.
> 
> Reblog the [thing](http://themadkatter13fanfiction.tumblr.com/tagged/Cuckolding-Isn%27t-Just-for-Men-Anymore).


End file.
